Magazine article Science News

New UN Soil Survey: The Dirt on Erosion

Magazine article Science News

New UN Soil Survey: The Dirt on Erosion

Article excerpt

Since World War II, more than 3 billion acres of agricultural land -- an area larger than China and India combined -- have been damaged by human actions and may prove costly or impossible to reclaim. This and related findings presented in a new United Nations report "confirm our worst fears about the degree to which soils are eroding and being degraded around the planet," says James G. Speth, president of the World Resources Institute (WRI) in Washington, D.C. It topsoil erosion continues at post-World War II rates, feeding an exploding world population could prove extremely difficult, he says.

"Each year the world's farmers are trying to feed 92 million more people with 24 billion tons less topsoil," comments agricultural economist Lester R. Brown, president of the Worldwatch Institute in Washington, D.C. "You don't have to have a Ph.D. in agronomy to understand that those two trends can't both continue indefinitely."

WRI released the UN-sponsored survey -- the first ever to chart soil health globally -- last week. The findings indicate that nearly 22 million acres of the world's land can no longer support vegetation and may have little hope of recovery. Another 740 million acres will require a restoration effort larger than most developing nations could organize. Some 2.3 billion acres more -- an area about the size of the United States -- require major and costly reclamation efforts, such as installation of drainage ditches.

In addition to erosion from wind and water, the survey mapped soil degradation from chemical sources, such as excessive levels of salt or pollution, and from physical sources, such as livestock or heavy machinery. The UN team of roughly 200 analysts attributes:

* 35 percent of soil erosion to livestock overgrazing, a problem that appears most widespread in Africa and Oceania. …

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